1. Field of the Invention
The present invention relates to fixing mechanisms, and more particularly, to a fixing mechanism fox fixing a planar member to a carrier board of an electronic product.
2. Description of Related Art
A conventional method of installing a PCB or an extension card of board-shaped structures in a computer or a server is to simply screw the PCB to bosses or other mounting structures suitably mounted on a chassis. However, this fixing method of installing a PCB by screws has disadvantages in operation as it necessitates the use of tools, the labor and the time spent in assembly and disassembly for replacement or maintenance purposes, decreasing the working efficiency as a result.
To increase the efficiency of installing a PCB in a computer, Taiwanese Utility Patent No. M269690 discloses an improved technique for fastening a PCB without using screws, as depicted in FIG. 1. As shown in the drawing, the fixing mechanism disclosed by Taiwanese Utility Patent No. M269690 fastens a PCB 1 onto a carrier board 4 formed with a plurality of fastening pillars 40, each fastening pillar consisting of a bottom portion 401, a neck portion 402 extending upward from the bottom portion 401, and a head portion 403 extending upward from the neck portion 402; the fixing mechanism is provided with a plurality of elastic tabs 2, wherein each elastic tab 2 consists of a protruding tip 22 disposed on the bottom surface, a first bending portion 24 disposed at a position away from the protruding tip 22, a fastening aperture 25 disposed between the protruding tip 22 and the first bending portion, an extending portion 28 disposed at a side position away from the protruding tip 22, and a positioning portion 29 disposed between the extending portion 28 and the first bending portion 24, wherein the fastening aperture 25 comprises a guide-in hole 251 and a mating hole 252.
In applying the foregoing fixing mechanism, the positioning portion 29 thereof is used to insert in a through aperture 16 of the PCB 1, while the pair of protruding tips 22 is inserted in the positioning aperture 14 of the PCB 1, allowing the elastic tabs to be clipped and held on the PCB 1; subsequently, the plurality of fastening pillars 40 formed on the carrier board 4 is inserted into the through hole 12 and the guide-in hole 251 to expose the head portion 403 of the fastening pillar 40, so as to push the PCB 1 so that the first bending portion 24 on the elastic tab 2 is pressed to elastically deform downwardly that enables the extending portion 28 to extend outward to a grounding tab 18, thereby fastening the PCB 1 onto the carrier board 4 by means of the clipping force generated from the flexible deformation of the elastic tab 2 when the neck portion 402 of the fastening pillar 40 slides into the mating hole 252. On the other hand, in disassembly, the PCB 1 is pushed to slide along in a reverse direction so that the neck portion 402 of the fastening pillar 40 slides into the guide-in hole 251 to disassemble the PCB 1.
While the above patented technique of using a plurality of elastic tabs to install a PCB eliminates the use of any auxiliary tool such as screws, it produces nevertheless other problems in that it necessitates using a plurality of elastic tabs in applying the technique, thereby inadvertently increasing the components required and the material cost as a result, and also creating an issue of components management as well for disassembling operation.
Moreover, as elastic tabs are unable to withstand and resist the level force of the PCB and thus liable to detach from a computer chassis when moving along at lateral directions that are caused by accidental vibrations or collisions. Further, the fastening pillars are generally produced by machinery processing and thus inherent with a common difference in manufacturing, and in the case that the perpendicular distance between the upper and lower surface of the neck portion thereof is made too big to completely press and tighten the first bending portion of the elastic tab, the elastic tab cannot be fully squeezed to deform and generate a sufficient clipping force that is necessary to clasp the PCB in position and is likely to cause the PCB to move up and down as a result.
Also, in the case of a PCB being installed in a non-plane surface, it is necessary to use auxiliary components or structures for support and prevent the elastic tabs from coming off, which reduces the convenience of installation in addition to the complexity of forming pluralities of through holes, positioning holes, penetrating holes and grounding tabs on the elastic tab to achieve the effect of fastening. In short, the use of elastic tabs advertently has drawbacks in that it may affect the design of a PCB wiring, reduce the flexibility of wiring design that may even force the wiring space to be reduced and thus limit the upgrade of functionality, and also occupy valuable spaces required for operation and configuration and goes against a development trend of miniaturization of electronic products.
Therefore, it is desirable to develop a novel mechanism to facilitate installation of a PCB in a computer that is easy, convenient to operate and also is economical.